1. Field of the invention
The present invention is generally concerned with operations to be performed on an ophthalmic lens before it is mounted on a bevel routing machine for shaping its contour to suit the ring or surround of the eyeglass frame to be fitted with the lens.
2. Description of the prior art
The first operation required is that of centering the ophthalmic lens relative to fixed markers and according to parameters taking into account the physiological characteristics of the person concerned.
The next operation is mounting on the ophthalmic lens centered in this way a holding and securing device, for example a simple suction cup or a plastic gland, used to fit it to and secure it on the bevel routing machine used.
These operations can be performed manually.
In practice, however, they are usually performed by means of a centering or mounting device designed for this purpose.
Generally speaking, these centering and mounting devices all comprise a base adapted to receive the opthalmic lens to be processed and to center it.
In somewhat rudimentary implementations which have the advantage of being economical, as is the case for example with those which are the subject matter of French Pat. Nos. 1 484 799 and 1 548 515, the ophthalmic lens to be processed is in practice placed directly onto the suction cup which is to be attached to it and the corresponding attachment is secured by pushing the ophthalmic lens down relative to the suction cup after it has been appropriately centered relative to the latter.
In American Pat. No 2 734 322 the lens is pushed down by means of an arm mounted to swing on a base.
Centering and mounting devices of this kind are not able to ensure that, before mounting takes place, the ophthalmic lens fits inside the contour of the ring or surround of the eyeglass frame to which it is to be fitted, given the centering that has been applied to it.
The same applies in more complex implementations, and this is the case with that which is the subject matter of French Pat. No. 2 188 182, for example, in which, before mounting takes place, the ophthalmic lens is compared with a template representing the ring or surround of the eyeglass frame to which the lens is to be fitted and in which the suction cup or, more generally, any other form of holding and securing means is placed on the ophthalmic lens with the aid of an arm mounted to swing on the base of the device and fitted to this end with a support adapted to receive a holding and securing device of this kind in a removable way.
However, these complex implementations are considerably more costly than those previously described because in practice they use illumination means and optical means such as semi-reflecting mirrors to superpose an image of the contour of the ophthalmic lens on that of the template to be followed.
A general object of the present invention is an arrangement for ensuring in a simple and economical way that the ophthalmic lens fits within the contour of any template.